The present invention is directed to a control circuit for automatically counterbalancing the moving components of a press.
It is well known that in a machine such as a press, it is necessary to keep the moving components in equilibrium by using air pressure to counterbalance the moving members on the eccentric such as a reciprocable ram having a die half mounted thereon. More specifically, in the operation of such a press, on the downstroke if there is excess counterbalancing then the press does more work than necessary causing excess wear on the moving parts, e.g., the flywheel, cam, etc. Similarly, on the upstroke of the ram, if there is insufficient counterbalancing, then the working members tend to fall away from the eccentric as the flywheel energy is restored.
Since each die used on a press has its specific configuration and weight, a change is required in the counterbalance to maintain equilibrium each time a different die is placed on the press.
In addition, in a variable speed press, the counterbalancing is a function of not only the die weight on the ram but also of the ram speed.
Under state and federal safety and health acts (for example, OSHA), it is necessary to identify the weight of a die on the upper half of the die and thereafter train operators to set the air pressure for counterbalancing. However, this does not account for various speeds of operation of the press.